live555: Use OPTIONS as keep-alive fallback
live555: Use OPTIONS as keep-alive fallback

So far no keep-alive messages are sent when GET_PARAMETERS is not supported by
the server. Change this to fall back to sending OPTIONS as keep-alive message,
which is the default keep-alive message in the SAT>IP specification. As
RFC2326 does not enforce a specific command as keep-alive message this shall
be valid for any compliant RTSP server.

Signed-off-by: Julian Scheel <354106e416911844661e1603d99ecf7d1c318dda@jusst.de>
Signed-off-by: Jean-Baptiste Kempf <7b85a41a628204b76aba4326273a3ccc74bd009a@videolan.org>

shyamalschandra/vlc,krichter722/vlc,vlc-mirror/vlc,shyamalschandra/vlc,krichter722/vlc,vlc-mirror/vlc,shyamalschandra/vlc,xkfz007/vlc,vlc-mirror/vlc,vlc-mirror/vlc,shyamalschandra/vlc,krichter722/vlc,krichter722/vlc,xkfz007/vlc,krichter722/vlc,xkfz007/vlc,vlc-mirror/vlc,krichter722/vlc,xkfz007/vlc,vlc-mirror/vlc,xkfz007/vlc,shyamalschandra/vlc,shyamalschandra/vlc,krichter722/vlc,xkfz007/vlc,vlc-mirror/vlc,xkfz007/vlc,shyamalschandra/vlc